Hi! I gave myself a challenge to create a TAS of smb1 in at least 4:57, but I just can't seem to get 1-1 fpg right. I don't need any nerdy statistics or anything, i just want a straightforward explanation as to what i'm doing wrong. I have this file on my drive that you can inspect so uh glhf!

side note: can you help me do the underground section better? do i just hold left for some frames after jumping?

For the FPG: You are not on the right subpixel. (In fact, it doesn't look like you attempted any kind of subpixel manipulation at all.) Knowing what the "right subpixel" is would take more words to explain than I feel like typing out right now, so just know that if you delete the B input on frame 1226 in your TAS (this is the frame that you land on the third-to-last step), and then extend your jump off of the stairs to be a full jump (keep the timing the same), then you'll be set up perfectly to get the FPG. In fact, this is what RTA runners do to get the FPG in this level, so if you didn't know that there was an extra setup there then I would recommend reviewing an any% tutorial to get up to speed on that.

For the underground: You are holding right way too late. Play around with the timing until you find the earliest frame that you can start holding right without bonking into the wall. Also, you should avoid bonking into the pipe at the end by holding left as much as you need to so that you land on the ground before/at the same time you touch the pipe.

k thx! i have no idea which bits correspond to subspeed, so i was kinda just winging it.

for TAS you can always just go fast and jump such that you would land barely on the goal block, then while in the air before landing you press left for 1 frame and then press no direction for X amount of frames before pressing right again, see how many null frames (frames with less speed) you need to not land in the block and instead just click perfectly for FPG